The invention relates to an axially staged annular combustion chamber of a gas turbine with a central axis, and with a plurality of pilot burners located between annular wall sections, as well as with main burners that terminate in the combustion chamber downstream from and radially outside the pilot burners. A main burner zone abuts the main burners. The combustion chamber includes an outer and an inner combustion chamber wall, each annular in shape. Each of the walls extends up to the combustion chamber outlet, with the inner combustion chamber wall having a wall section that runs essentially parallel to the pilot burner axis in the area of the pilot burner zone.
Regarding known prior art, reference is made for example to WO 93/25851 (having a U.S. equivalent in U.S. Pat. No. 5,406,799) or German Patent document DE-OS 28 38 258, but especially to GB-A-2 010 408 (having a U.S. equivalent in U.S. Pat. No. 4,194,358), showing an axially staged annular combustion chamber in which the combustion gases of the pilot burner zone are conducted by an appropriate design, especially of the inner combustion chamber wall, into the main burner zone.
The goal of the present invention is to improve an axially staged annular combustion chamber of the above-mentioned type, especially in regard to the mixing of the pilot burner gases with the main burner gases and thus to the exhaust emissions and/or the temperature distribution in the vicinity of the combustion chamber outlet.
To achieve this goal, provision is made such that the inner combustion chamber wall, adjoining the inner wall section that forms the pilot burner zone and essentially also runs parallel to the central axis, has a deflecting section that is convex-concave in shape. The deflecting section runs toward the main burner zone as viewed looking downstream, i.e. as viewed from inside the combustion chamber. The deflecting section, viewed in the radial direction relative to the central axis, extends approximately at the level of the outer pilot burner wall section. The deflecting section is abutted by a wall section that leads to the combustion chamber outlet and runs essentially parallel to the central axis.
An additional measure consists in that the outer wall section of the pilot burner zone that faces the main burner runs at an angle to the lengthwise axis of the associated pilot burner, so that the cross section of the pilot burner zone decreases in the flow direction. Advantageous improvements and embodiments are described herein.
The invention will now be described in greater detail with reference to two preferred embodiments as shown in the drawings.